Process for transmitting a hydrocarbon fluid through a pipeline

ABSTRACT

Many liquids have properties improved, and fluid flow friction losses are reduced in flowing fluids by adding thereto a small, effective amount of composition comprising (i) a continuous phase of a liquid which is normally miscible with said fluid, and, dispersed therein, (ii) a stable discontinuous phase predominantly comprising fine particles of a high molecular weight polymer which is ultimately miscible with said fluid. In preferred features the compositions include a surface active agent. In other preferred features, friction is reduced in flowing hydrocarbons.

The present invention relates to compositions and methods for improvingproperties of liquid media and particularly for reducing friction lossesin flowing hydrocarbon fluids. It also concerns a method for producingsuch compositions by in situ polymerization.

BACKGROUND OF THE INVENTION

Linear polymers of high molecular weight, includingpolydiorganosiloxanes as well as various organic polymers are known aseffective agents for improving the flow, spreadability, wear resistanceand other characteristics of liquid media, such as polishes, cosmetics,and the like. Also known is their ability to increase the flow of crudeoils and refined petroleum products through pipelines. See, for example,Canevari et al, U.S. Pat. No. 3,493,000; Martellock, U.S. Ser. No.72,193, filed on Sept. 14, 1970, now abandoned and assigned to theassignee of the present application; White et al, U.S. Pat. No.3,215,154; Gibson, U.S. Pat. No. 3,351,079; Seymour et al, U.S. Pat. No.3,559,664; British Pat. No. 1,319,098; Culter et al, U.S. Pat. No.3,692,676; and Kruka et al, U.S. Pat. No. 3,687,148.

It is well known that such high polymers as drag reduction additivesmust be in solution in the liquid media, e.g., a flowing liquidhydrocarbon, e.g., crude or refined oil, in order to be effective.However, the practical attainment in the liquid media of homogeneoussolutions of suitable concentration, typically 10-2000 ppm of polymer,has heretofore presented serious engineering and economic problems.Polymers of the required high molecular weight are hard gums, slow todissolve, and direct injection of bulk polymer is completelyimpractical.

To date in laboratory and field tests, with pipeline fluids, it hasproven convenient to inject previously prepared "master batch" solutionsin hexane, kerosene, and the like. However, at levels of full scale use,which approach millions of pounds of additive annually, serious problemsarise in the production, shipment and storage of such solutions.

One basic problem is the very high viscosity of master batch solutions,because of the necessarily high molecular weight of the drag-reducingpolymer. Above a concentration limit of about 5 percent, the viscositybecomes so high that such solutions become impractical for injectionpumping, and also very difficult to produce at uniform and controlledconcentration. The cost of purchase and shipment of such large amountsof solvent in relation to active polymer is a serious burden.

A second basic problem is that the process of dissolving the hard gumsordinarily employed is inherently lengthy and expensive. Agitativeintensity must be kept low to avoid shear degradation of the dissolvedpolymer to shorter chains, because these are ineffective as dragreducers. This requires costly investment in very bulky equipment ofunconventional type.

Although it is possible to ship the polymer in bulk and to convert it tomaster batch at the injection site, typically using part of the pipelinecontents as "free" solvent, in practical terms, the number of separatedissolving machines becomes prohibitive. Users strongly prefer insteadto employ a formulated product ready for injection, rather than to beencumbered with dissolving operations.

It has previously been proposed that a more convenient drag reductionproduct might be made by milling bulk high polymer resin into fineparticles, which will dissolve more readily. These, however, tend toreagglomerate on standing, and means of preventing reagglomeration havenot been found. Further, in all processes involving mechanicaldisintegration of bulk resin, whether or not in the presence of asecond, non-solvent liquid phase (for example by milling, colloidmilling, homogenizing, and the like), there is grave risk of sheardegrading the polymer.

It has now been discovered that novel two-phase compositions of liquidmedia modifying and drag-reducing polymers can be produced, and theseovercome all of the above-mentioned problems. Basically, each suchcomposition consists of a disperse phase of fine particles ofdrag-reducing polymer, suspended in a continuous liquid phase comprisinga non-solvent for that particular polymer. As a further requirement, thecompositions of both disperse and continuous phase are so selected as tobe soluble in the hydrocarbon media (the pipeline stream.)

The new compositions of this invention have the following advantages:

(1) They can contain as much as 50 percent or more of drag-reductioneffective polymer at readily pumpable consistencies.

(2) In preferred cases, and according to one aspect of the invention,the polymer can be formed in situ as the final disperse phase, with verysignificant elimination of processing steps and degradation hazard.

(3) The laborious operation of dissolving high polymer, and the need forusing large volumes of solvent are entirely eliminated.

In addition, they appear to be longer acting than prior artcompositions. This seems to result from the fact that under pipelineflow conditions, only dissolved polymer suffers shear degradation;suspended particles are immune. The smallest particles dissolve mostrapidly, while larger droplets dissolve more gradually during passagealong the pipeline. This results in continuous replenishment of thelongest, most effective molecules in solution, directly offsetting anyloss due to shear degradation. With adequate control of particle sizedistribution, benefits approximating those of multiple injection sitesalong the line can be obtained with the economy of a single injection.This controlled rate of solution principle bears a partial analogy tothe 12 hour cold capsule, which releases medication slowly.

DESCRIPTION OF THE INVENTION

According to the present invention, there are provided compositions forimproving liquid media and for reducing the fluid flow friction loss inthe transmission of a hydrocarbon fluid through a pipeline, saidcompositions comprising:

(i) a continuous phase of a liquid which is normally miscible with saidliquid media, e.g., hydrocarbon fluid, and, dispersed therein,

(ii) a stable discontinuous phase predominantly comprising fineparticles of a high molecular weight polymer which is ultimatelymiscible with said liquid media, e.g., hydrocarbon fluid.

Another preferred feature of this invention is providing processes fortransmitting a hydrocarbon fluid through a pipeline at a reduced fluidflow friction loss, which comprise:

A. intermixing with said fluid a composition comprising:

(i) a continuous phase of a liquid which is normally miscible with saidhydrocarbon fluid, and, dispersed therein,

(ii) a stable discontinuous phase predominantly comprising fineparticles of a high molecular weight polymer which is ultimatelymiscible with, and normally difficult to solubilize in, said hydrocarbonfluid, the amount of said composition being selected to provide from 10ppm to 1500 ppm of high molecular weight polymer based on saidhydrocarbon fluid; and

B. transmitting the resulting mixture through a pipeline at a velocitysufficient to establish turbulent flow conditions.

According to a preferred aspect, the present invention contemplates aprocess for producing a liquid media modifying composition comprising:

(i) dissolving or suspending a monomer capable of forming a highmolecular weight polymer, or optionally a mixture of monomers capable offorming a high molecular weight copolymer, in a continuous phase-formingliquid which is normally miscible with said liquid media; and

(ii) subjecting the monomer or monomers to polymerization conditions soas to produce a stable discontinuous phase predominantly comprising fineparticles of high molecular weight polymer ultimately miscible with saidliquid media and dispersed in a continuous phase in said continuousphase-forming liquid.

Preferably, the monomer will be a silicone precursor, e.g.,octamethylcyclotetrasiloxane; a preferred continuous phaseforming liquidis heavy mineral oil or a methylnaphthalene or mixture thereof havingfrom one to three methyl groups per molecule. In another preferredfeature, the monomer will be polymerized in the presence of a transientcatalyst, e.g., tetrabutylphosphonium silanolate, at an elevatedtemperature, e.g., 50°-125° C., preferably 80°±10° C., and then thecatalyst will be destroyed by heating at a higher temperature, e.g.,125°-200° C., preferably at about 150°±10° C. Preferred high molecularweight polymers will be polydiorganosiloxanes in which 20 to 100 percentof the organic groups linked to silicon are methyl groups and theremainder are phenyl groups.

In other preferred features, the invention will be used with hydrocarbonfluids comprising crude oil and refined petroleum products, e.g.,gasoline, kerosene, distillate fuel oil, jet fuel oil, liquifiedpetroleum gas, pentane, cyclohexane, isooctane, toluene, mixturesthereof, and the like. The preferred high molecular weight resins willbe polyhydrocarbons or polydiorganosiloxanes, each having an averagemolecular weight of at least 500,000, and preferably above 1 million upto about 40 million. If the drag-reducing polymer is a polyhydrocarbon,preferred liquids which are normally miscible with the hydrocarbonfluids are selected from a monohydric alcohol of from 1 to 16 carbonatoms; a dihydric alcohol for from 7 to 16 carbon atoms; an ester of amono or polyhydric alcohol of from 1 to 16 carbon atoms and an acid offrom 6 to 30 carbon atoms; a polyoxyalkylene dialkyl ether; or ahydrocarbon solution of a second polymer of lower molecular weight andcomposition chemically different from that of the high molecular weightpolyhydrocarbon. If the drag-reducing polymer is a polydiorganosiloxane,the preferred liquid which is normally miscible with the hydrocarbonfluids is a liquid hydrocarbon oil of average molecular weight of lessthan about 2000; optionally, but preferably, these compositions willalso include a surface active agent comprising apoly(methylalkyl)siloxane fluid.

Factors affecting the consistency of the present drag-reducingcompositions are primarily the viscosity of the continuous phase, andalso the volume percent of disperse phase, especially when the latterexceeds about 50 percent. While there are no rigid upper limits, forconvenience in handling and pumping it is desirable that the continuousphase have a viscosity not exceeding about 2000 cps. at 25° C.

The range of compositions embraced by this invention is very broad,extending over both silicone and non-silicone polymers. Illustrativeembodiments are:

1. A linear hydrocarbon polymer dispersed in one of the following:

(a) a non-solvent monohydric alcohol of 1 to 16 carbon atoms;

(b) a non-solvent dihydric alcohol of at least 7 carbon atoms;

(c) a non-solvent ester, e.g., a mixed fatty acid glyceride such asvegetable oil;

(d) a non-solvent polyoxyalkylene dialkyl ether, e.g., tetraethyleneglycol dimethyl ether; or

(e) a hydrocarbon solution of a second polymer of lower molecular weightand composition dissimilar to the dispersed polymer; and

2. A polydiorganosiloxane dispersed in a non-solvent hydrocarbon, e.g.,white mineral oil or an aromatic process oil.

To promote physical stability of these compositions, which may be termedoil-in-oil emulsions, it is preferred to incorporate a suitablesurfactant material selected for non-interference with the method ofpreparation and with the drag reduction function. The role of thesurfactant is to promote a fine state of sub-division of the dispersephase and to retard its rate of coalescence.

Surprisingly, there is almost a complete absence in the prior art ofemulsions in which neither phase is aqueous. It was not until 1965 thatMolau, Journal of Polymer Science A 3(4), 1267-1278 provided a"verification of the existence of oil-in-oil emulsions".

A very few earlier workers disclosed dispersions of polyhydrocarbons orof vegetable oils in non-aqueous continuous phases including glycerol,formamide or ethylene glycol; but the latter are all water-miscible andhydrocarbon-immiscible, and therefore none of these earlier systemswould be suggestive of the present discovery.

As has been mentioned, suspensions of linear polydiorganosiloxanes inselected hydrocarbon oils represent one preferred class of theinvention. According to this invention, there can be used an in situpolymerization of an initially homogeneous solution of cyclicsiloxane(s) in the hydrocarbon oil. The linear polymers thus produced,upon reaching a relatively low polymer stage, separate from thehydrocarbon phase as microscopic droplets. Polymerization continueswithin these droplets until high molecular weight is reached.

In a preferred silicone-in-hydrocarbon embodiment, exemplifiedhereinafter, a transient catalyst, e.g., tetrabutylphosphoniumsilanolate is used; the polymerization is run at a conventionaltemperature range, e.g., 80°±5° C. for such catalyst, and afterpolymerization is complete the catalyst is destroyed by heating to ahigher temperature. As is disclosed in the above-mentioned Martellockapplication, these materials have superior resistance to degradationduring use as drag-reduction agent. Alternatively, the catalyst may bean alkali metal silanolate, typically effective at higher temperatures,and the final suspension may be decatalyzed by addition of suitabletrace amounts of soluble acid, e.g., an aliphatic carboxylic acid or anaphthenic acid.

Certain poly(methylalkyl)siloxane fluids chainstopped by trimethylsilylgroups have been found to be effective dispersing agents in the abovepolydiorganosiloxane-hydrocarbon oil systems, as detailed hereinafter.

As has been mentioned, suspensions of linear polyhydrocarbons inselected liquids as continuous phase media represent another preferredclass of the invention. The polyhydrocarbons can be any of thedrag-reducing polyhydrocarbons of the prior art, such as polyisobutene,polyisoprene, polybutadiene, ethylene-propylene copolymers,olefin-styrene copolymers, etc., or they may be novel linearpolyhydrocarbons such as isoprene-butadiene random copolymers,polyisobutene-polybutadiene block copolymers, etc., provided only thatthe average molecular weight is at least 500,000 and preferably onemillion or greater.

In general, the continuous phase media of this class are liquids whichare (1) non-solvents for the selected high molecular weight linearpolyhydrocarbon, and (2) miscible with liquid hydrocarbons of averagemolecular weight less than about 2000. A preferred group of media whichmeet these criteria are aliphatic monohydric alcohols of 1 to 16 carbonatoms, e.g., methanol, hexanol, isooctanol, decanol, hexadecanol, etc.Another preferred group comprises selected esters meeting the abovecriteria, for example mixed fatty acid glycerides such as cottonseedoil, peanut oil, and soybean oil. Low-cost, inedible grades of theseoils are satifactory in the present invention.

In general, as will be understood by those skilled in this art, simpleliquid hydrocarbons or refined petroleum oils within the usefulviscosity range (<2000 cps), such as those detailed in the polysiloxaneexamples hereinafter, tend to dissolve linear polyhydrocarbons, and aretherefore unsatisfactory as continuous phases because extremely viscoussolutions are formed rather than the desired two-phase suspensions.Exceptions may exist where the solubility parameters of polymer andliquid differ by an unusually large amount. However, without recourse tosuch exceptions, a wide range of low-cost hydrocarbon liquids and oilscan nevertheless be used, by taking advantage of the well-knownphenomenon of mutual exclusion from solution of dissimilar polymers.Specifically, systems comprising three components, as follows:

(1) linear polyhydrocarbon, >MW 500,000, δ=x

(2) low polymer, MW 50,000, δ=y

(3) oil, MW 900, δ=z

where x and y are substantially dissimilar, and y and z are much closerto each other than they are to x, exist as a stable two-phase system inwhich there is

(i) a continuous phase containing all of the low polymer and nearly allof the oil, and

(ii) a disperse phase containing all of the high polymer and a smallpart of the oil.

In such a system, the low polymer (2) need not be a polyhydrocarbon. Itcan be a chemically different low polymer, such as a polyvinyl acetate,a polyoxyalkylene ether or a polysiloxane.

In order to promote and maintain a fine dispersion, a practicalsuspension of this general model will also preferably contain asurfactant, chosen for preferential compatibility with the oil-lowpolymer phase in order to favor the latter as the continuous phase(Bancroft's Rule).

In the practice of the method of the present invention, the compositionis intermixed with the liquid to be transported, and the liquid ispumped and transferred in conventional manners, as described in thepatents above-mentioned. While significant reduction in frictionallosses are observed using polymers having a viscosity average molecularweight of as low as 500,000, it is preferred that the high polymers havea molecular weight in the range of from about 1 million to about 40million and preferably in the range of from about 7 million to about 20million. The compositions afford effective reductions in drag when thepolymer component dissolves in the hydrocarbon fluid to provide aconcentration of at least 5 parts per million (ppm), although they arepreferably employed in the range of from 10 ppm to 1500 ppm. The optimumamount will vary, depending on the molecular weight of the polymer, thenature of the hydrocarbon fluid and the flow conditions of the fluid.Those skilled in the art are well aware of these effects.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following examples are illustrative of the present invention. Theyare not intended to limit the scope of the invention in any mannerwhatsoever.

EXAMPLE 1

Thirty-six grams of extra heavy white mineral oil, 27.5 g. ofoctamethylcyclotetrasiloxane, and 0.5 g. of trimethylsilyl-stoppedpoly(methylalkyl)siloxane (surfactant, General Electric Co., SF-1100)are heated in an oil bath and stirred under nitrogen at a pottemperature of 133° C. for 1 hour for azeotropic drying, during which1.2 g. of the (Me₂ SiO)₄ is vaporized from the flask. The bathtemperature is then reduced to 95° C. and 10 drops of Bu₄ P silanolatecatalyst is added to the clear mixture. Within 10 minutes haze is seenindicating separation of a polydimethylsiloxane phase. Thereafter, theopacity and the amount of siloxane disperse phase increases rapidly.After 2.1 hours at 94°-95° C., a sample is taken via hypodermic syringewithout needle. The intrinsic viscosity in toluene at 25.0° C. is 1.45dl/g., viscosity average molecular weight 800,000.

After 4 days of aging at room temperature, this suspension is still welldispersed and shows no tendency to agglomerate. Microscopic examinationshows that a large proportion of the resin droplets are in the 3-4micron diameter range.

The composition upon addition to hydrocarbon fluid, in an amount toprovide from 10 to 1500 ppm of silicone polymer content, is effective toreduce the frictional drag on the fluid upon transfer through apipeline.

EXAMPLE 2

Instead of a white mineral oil as in Example 1, an aromatic process oilis used to suspend the polydimethylsiloxane particles. Flexon 391, acommercial product (Exxon Company) sold under the followingspecifications:

    ______________________________________                                        Density         0.9745                                                        Viscosity       866 csk at 100° F.                                     Composition, %: Aromatics    66.5                                                             Saturates    30.5                                                             Polar compounds                                                                            3.0                                              ______________________________________                                    

is treated to remove catalyst-reactive impurities by passing ahexane-Flexon 391 mixture through a bed of activated alumina andstripping off the hexane under dry nitrogen. A mixture of 19.14 g. ofthe purified Flexon oil and 18.00 of (Me₂ SiO)₄ and 0.5 g. oftrimethylsilyl-stopped poly(methylalkyl)siloxane surfactant isazeotroped dry (1.93 g. D₄ distilled) and polymerized as in Example 1.Five minutes after addition of catalyst (20 drops Bu₄ P silanolate) at90° C. a heavy cloud appears. After 4.4 hours at 80°±10° C. the polymeris a smooth suspension of fine polydimethylsiloxane droplets with amolecular weight of 960,000.

The composition upon addition to hydrocarbon fluid, in an amount toprovide from 10 to 1500 ppm of silicone polymer content, is effective toreduce the frictional drag on the fluid upon transfer through apipeline.

EXAMPLE 3

Instead of a white mineral oil as in Example 1, a methylnaphthalenefraction of petroleum origin is used to suspend the polydimethylsiloxaneparticles. Methylnaphthalene No. 2, a commercial product of CrowleyHydrocarbon Chemicals, Inc., is treated to remove catalyst-reactiveimpurities by passing it through a bed of activated alumina. A mixtureof 16.20 g. of the purified methylnaphthalene, 10.48 g. of (Me₂ SiO)₄and 0.2 g. of trimethylsilyl-stopped poly(methylalkyl)siloxanesurfactant is azeotroped dry and polymerized as in Example 1. After 20hours at 86°±4° C., the polymer is a smooth suspension of finepolydimethylsiloxane droplets with a molecular weight of 6,690,000.

The composition upon addition to hydrocarbon fluid, in an amount toprovide from 10 to 1500 ppm of silicone polymer content, is effective toreduce the frictional drag on the fluid upon transfer through apipeline.

A common method of preparing linear polyhydrocarbons is emulsionpolymerization of the corresponding olefins, or mixtures thereof. Theresult is a latex of polyhydrocarbon dispersed in a water-surfactantmedium. These are commercially available in wide variety. While themolecular weights of many commercial latices may be too low foreffective drag reduction, in general higher molecular weights, in thedrag reduction range, are obtainable by suitable modification ofpolymerization conditions. A non-aqueous suspension for direct use inpipeline hydrocarbon streams is made by replacing the water phase of alatex with a water-soluble, hydrocarbon-soluble organic liquid, asdisclosed above. With due consideration of the nature of surfactantagent(s) already present, and possibly the addition of further suitablesurfactant, such replacement can be made without substantial coalescenceof the emulsion.

EXAMPLE 4

A styrene-butadiene copolymer latex (General Aniline and Film Co.,GAF1400) 60 percent disperse phase, is blended with two volumes of a 1:1water-tetraethylene glycol dimethyl ether solution with no visiblecoagulation or other change. The water is then removed by vacuumdistillation to give a dispersion of butadiene-styrene copolymer intetraethylene glycol dimethyl ether, both phases of which are soluble indistillate fuel oil, gasoline, and other liquid hydrocarbons.

The composition upon addition to hydrocarbon fluid, in an amount toprovide from 10 to 1500 ppm of resin copolymer content, is effective toreduce the frictional drag on the fluid upon transfer through apipeline.

The procedure is repeated with water based latices of polyisobutylene,polyisoprene, polybutadiene and polymers and copolymers of ethylene,propylene and alpha olefins of from 4 to 20 carbon atoms. There areobtained drag reducing compositions according to this invention in whichthe liquid phase is tetraethylene glycol dimethyl ether.

EXAMPLE 5

By conventional methods, e.g., Drukker, U.S. Pat. No. 3,635,863, anemulsion is formed using a vegetable oil (e.g., cottonseed, peanut) plussurfactant as continuous phase, and the preformed polymer-in-waterstyrene-butadiene copolymer latices of Example 4 as disperse phase. Theresult is a three-phase, oil-in-water-in-oil emulsion. The water is thenremoved in vacuo leaving a very fine polymer-in-oil suspension suitablefor drag reduction in pipelines.

The procedure is repeated with water-based latices of polyisobutylene,polyisoprene, polybutadiene and polymers and copolymers of ethylene,propylene and alpha olefins of from 4 to 20 carbon atoms. Substantiallythe same results are obtained.

EXAMPLE 6

Polyisobutylene (m.w. 10,000,000) is dissolved in methylene chloride andmixed with hexadecanol to provide a homogeneous solution. Selectivedistillation of the methylene chloride leaves a suspension of fineparticles of polyisobutylene in hexadecanol which is suitable for use asa drag reducing composition according to this invention. The procedureis repeated, adding a small amount of a surface active agent. A dragreducing composition according to this invention is formed.

EXAMPLE 7

Polyisobutylene (m.w. 10,000,000) is dissolved in kerosene and mixedwith a kerosene solution of a polyalkylene oxide (m.w. 10,000-200,000)and a soluble surfactant. The resulting dispersion is concentrated bydistillation at reduced pressure and provides an efficientlytransportable drag reducing composition according to the presentinvention.

EXAMPLE 8

An ethylene-propylene copolymer (m.w. 1,000,000) is prepared as adispersion in pentane by using a catalyst comprising a trialkylaluminumand vanadium chloride with an olefin feed containing 20 to 75 mole %ethylene. This dispersion is suitable for use directly, or with anoptional surfactant, as a drag reducing polyhydrocarbon according tothis invention.

While the above detailed examples describe useful compositions accordingto this invention, many obvious variations will suggest themselves tothose skilled in this art. The polydimethylsiloxane resins can bereplaced in whole or in part with polymethylphenyl orpolydiphenylsiloxane unit-containing resins. Suitable surfactants cancomprise tall oil, red oil, and commercial anionic and cationicsurfactants such as Alamine, Aliquat 21, Priminox 10, Primene JMT,Redicote 2323, all used in the weight percent range of from 0.10 to 3%by weight.

The silicone compositions are uniquely suited to provide improvedpolishes, cosmetics and the like because they avoid the need to mill orotherwise break up hard chunks of very high molecular weight resins.

All such variations are within the scope of the present invention asdefined by the appended claims.

I claim:
 1. A process for transmitting a hydrocarbon fluid through apipeline at a reduced fluid flow friction loss, which comprises:A.intermixing with said fluid a composition comprising: (i) a continuousphase of a liquid which is different from but normally miscible withsaid hydrocarbon fluid, said liquid being selected from the groupconsisting of a monohydric alcohol of from 1 to 16 carbon atoms; adihydric alcohol of from 7 to 16 carbon atoms, an ester of a mono orpolyhydric alcohol of from 1 to 16 carbon atoms and an acid of from 6 to30 carbon atoms; and a polyoxyalkylene dialkylether; and, dispersedtherein, (ii) a stable discontinuous phase predominantly comprising fineparticles of a high molecular weight polymer which is ultimatelymiscible with said hydrocarbon fluid, said high molecular weight polymerbeing a polyhydrocarbon having an average molecular weight of at least500,000, the amount of said composition being selected to provide from10 ppm to 1500 ppm of high molecular weight polymer based on saidhydrocarbon fluid; and B. transmitting the resulting mixture through apipeline at a velocity sufficient to establish turbulent flowconditions.
 2. A process as defined in claim 1 wherein said compositionalso includes:(iii) a surface active agent which is preferentiallycompatible with continuous phase (i) so as to favor the maintenance of(i) as the continuous phase and (ii) as the discontinuous phase.
 3. Aprocess as defined in claim 1 wherein the hydrocarbon fluid is a crudeoil or a refined petroleum product.
 4. A process as defined in claim 3wherein said hydrocarbon fluid is a refined petroleum product selectedfrom gasoline, kerosene, distillate fuel oil, jet fuel oil, liquifiedpetroleum gas, pentane, cyclohexane, isooctane, toluene, and mixturesthereof.
 5. A process for transmitting a hydrocarbon fluid through apipeline at a reduced fluid flow friction loss, which comprises:A.intermixing with said fluid a composition comprising: (i) a continuousphase of a liquid which is different from, but miscible with, saidhydrocarbon fluid, said liquid being a hydrocarbon oil of averagemolecular weight of less than about 2,000, and, dispersed therein, (ii)a stable discontinuous phase predominantly comprising fine particles ofa polydiorganosiloxane having an average molecular weight of at least500,000, the amount of composition being selected to provide from 10 ppmto 1500 ppm of said polydiorganosiloxane based on said hydrocarbonfluid; and B. transmitting the resulting mixture through a pipeline at avelocity sufficient to establish turbulent flow conditions.
 6. A processfor transmitting a hydrocarbon fluid through a pipeline at a reducedfluid flow friction loss, which comprises:A. intermixing with said fluida composition comprising: (i) a continuous phase of a liquid which isdifferent from, but miscible with said hydrocarbon fluid, said liquidbeing a hydrocarbon oil of average molecular weight of less than about2,000; and dispersed therein, (ii) a stable discontinuous phasepredominantly comprising fine particles of a polydiorganosiloxane havingan average molecular weight of at least 500,000, said composition alsoincluding (iii) a surface active agent which is preferentiallycompatible with continuous phase (i) so as to favor the maintenance of(i) as the continuous phase and (ii) as the discontinuous phase, theamount of composition being selected to provide from 10 ppm to 1500 ppmof said polydiorganosiloxane based on said hydrocarbon fluid; and B.transmitting the resulting mixture through a pipeline at a velocitysufficient to establish turbulent flow conditions.